Flexible corona discharge electrode with means to vary the length of the emitting portion



Aug. 1, 1967 M. CIPRIANI 3,334,227

FLEXIBLE CORONA DISCHARGE ELECTRODE WITH MEANS TO VARY THE LENGTH OF THE EMITTING PORTION Filed March 17, 1965 /"D7 T T N r -a- I I 1 EL United States Patent FLEXIBLE CORONA DISCHARGE ELECTRODE WITH MEANS T0 VARY THE LENGTH OF THE EMITTING PORTION Mario Cipriani, Florence, Italy, assignor to S.C.A.E. Societa Costruzioni Apparecchi Elettronici S.r.l., Florence, Italy, an Italian corporation Filed Mar. 17, 1965, Ser. No. 440,489 Claims priority, application Italy, Mar. 24, 1964, 6,234/ 64 Claims. (Cl. 250-495) ABSTRACT OF THE DISCLOSURE An electrode having an elongated guide and an elongated, flexible electrically conducting element extending adjacent said guide and anchored thereto at two spaced locations. Two sliding blocks are mounted on the guide and engage the flexible element to position the portion thereof between the blocks further from the guide than the adjacent portions whereby when the electrode operates on the material to be treated which passes on a surface facing said electrically conducting element, corona discharge from said element will be restricted to that portion of said element between the blocks which will be closer to said surface.

The invention relates to apparatus for effecting an electrical surface treatment of polythene or like materials surfaces, by corona etfect, to render the surface suitable for indelible printing thereon.

Such apparatus can be used to effect continuous treatment of a strip or flattened tube of material which is passed under an electrode or the active portion of the electrode, generating the corona effect, the material being moved over a roller which may be metallic or coated with an electrically insulating material. It is desirable that the position and'length of the active portion of the electrode should be variable to suit the position and the transverse dimension of the material being treated, in order to avoid the discharge from the electrode passing outside the material, or to avoid the discharge missing the edge portions of the material. It is also desirable that the length and position of the active portion of the electrode should be variable during the treatment, despite the fact that a high voltage is applied to the electrode.

According to the present invention there is provided an electrode for effecting an electrical surface treatment of polyethylene or like materials to render the surface suitable for printing thereon, said electrode comprising an elongated, flexible electrically-conducting element extending adjacent an elongated guide and anchored at two spaced positions on said guide, and two blocks independently slidable on said guide intermediate said positions, each block imposing a deviation on said element such that the portion of the element extending between the blocks is spaced further from said guide than the adjacent portions of the element.

The present invention also provides an electrode for effecting an electrical surface treatment of polyethylene or other material to render the surface suitable for printing thereon comprising an elongated guide having two blocks mounted for movement therealong and an elongated electrically-conducting element which extends adjacent said guide and passes slidably through said blocks in such a manner that the portion of the element between the blocks is spaced further from the guide than the portions of the element extending on the opposite sides of the block.

Thus by moving one of the blocks along the guide, the length of the portion of the element lying between Patented Aug. 1, I967 ice The invention will be better understood from the following description of one construction of apparatus in accordance with the invention which is given, by way of example only, and illustrated in the accompanying drawings in which:

FIGURE 1 is a side view of the apparatus showing an electrode which comprises a wire electrode element supported on a guide to extend close to material passing over a roller;

FIGURES 2A and 2B show two enlarged portions of the apparatus of FIGURE 1;

FIGURES 3, 4 and 5 are cross-sections taken along the lines IIIIII, IVIV, and V-V of FIGURE 23.

As shown in the accompanying drawing, the apparatus comprises a roller 1 over which passes the material M,

which is to be treated, and an electrode comprising an elongated flexible element E mounted on a support so that its active portion extends transversely of the material and in close proximity thereto.

The electrode further comprises two end support members 2, 3, between which extends a guide 5. The support members carry two hinges, such as that shown at 4 in FIGURE 2B, to permit rotation of the guide 5 about an axis extending parallel to the roller 1 between the two support members. The guide 5 comprises a channel member whose crosssection is rectangular, and more particularly, square (see FIGURES 4 and 5) over at least the central portion thereof.

Two blocks P P are slidably mounted on the guide 5. The two blocks are similar and symmetrical, and therefore only one of them, P is shown in detail. The block P includes two side plates 6 which are interconnected by pins 7 and held in spaced relationship on opposite sides of the guide 5 by spacers 7a.

The wire element E passes through the block P under a first roller 13 mounted on a pin 10 extending between the side plates, then over a second roller 14 mounted on a pin 7 through a bearing 8, and then over a pinion 12 mounted on a pin 9 extending between the side plates 6, the pinion being formed with a recess defining a track for the element E. (The first roller in block P is referenced 13a.) The pin 9 is former with an extension 9a to permit the pinion 12 to be driven.

The pinion 12 is provided with teeth 12a, which are adapted to mesh with a rack 16 on the guide 5. The arrangement permits the blocks P and P to be moved by rotation of an electrically-insulated tool engaging the extensions 9a of the pins 9. The movements of the two blocks are independent of one another.

The element E is a flexible metal conductor, in particular a wire, and is secured to a fixed point 17 on the guide 5 adjacent the support member 2, and is anchored at 18 on the other end of the guide 5 adjacent the support member 3, by means of a tensioning spring 19.

By means of the above-described arrangement, the portion of the element, which extends between the two rollers 13 and 13a of the two blocks P and P respectively, may be varied either in position by equal movement of the two blocks, or in length by movement of only one of the blocks or of both blocks by diflerent amounts. It will thus be seen that the moving operations are simple andsafe to perform, and moreover can be carried out during the processing of the material.

The active portion of the electrode E, between the two blocks P P is spaced from the rotational axis of the hinges, such as 4 in FIGURE 2B. Consequently, by slackening a pressure brake or the equivalent, by operation, for example, of a lever 20 it is possible to rotate the electrode to move the active portion of the element E away from the roller ll, to facilitate operations on the material M or for other purposes.

The drawing illustrates only one embodiment of the invention, and this can be varied substantially without departing from the scope of the invention as defined by the claims appended hereto.

Thus the blocks may be moved in a different manner, for example by threaded bar helical couplings independent of one another or connected to each other. The threaded bars may be arranged, for example, to rotate on the guide and to be driven by threaded halfnuts carried by the blocks, or on the contrary, threaded bars may be assembled on the blocks and coupled to halfnuts carried by the guide. A single operating bar may operate the two blocks with two threads, for simultaneous and symmetrical control.

The flexible conducting element may have a flat rectangular cross-section as shown, andlor alternatively a circular, square, triangular or any other suitable crosssection.

I claim:

1. An electrode for effecting an electrical surface treatment of polyethylene and like materials to render the surface thereof suitable for printing thereon, said electrode comprising an elongated guide,

an elongated flexible electrically-conducting element extending adjacent said guide,

means anchoring said element at two spaced anchorage positions on said guide,

two blocks,

means mounting said blocks for independent sliding movement along said guide intermediate said anchorage positions, and

means on each said block engaging said element for imposing a deviation on said element such that the portion of the element extending between the blocks is spaced further from said guide than the adjacent portions of the element whereby when the material to be treated passes on a surface facing said electrically conductive element, corona discharge from said element will be restricted to that portion of said element between the blocks which will be closer to said surface.

2. An electrode according to claim 1 further comprising resilient means connecting said element to the anchoring means at one of said anchoring positions.

3. An electrode according to claim 1 wherein said flexible element is a wire.

4. An electrode according to claim 1 further comprising a roller mounted in each said block, the said portion of the element extending between said blocks being extended around each said roller in a direction toward the guide.

5. An electrode according to claim 4 further comprising a second roller in each said block, said element extending from the first said roller passing around the sec- 4:- ond roller and thereafter extending alongside the guide in closer proximity thereto than said portion of the element extending between the blocks.

6. An electrode according to claim 1 comprising driving means associated with each block, for moving said blocks along said guide.

7. An electrode according to claim 6 wherein said driving means comprises a pinion member and a rack member extending parallel to said guide, said members being in meshing engagement with one another, one of said members being mounted on each said block and the other of said members being mounted on said guide, and means for rotating said pinion member thereby to move said rack member.

8. An electrode according to claim 6 wherein said driving means comprise a screw-threaded bar member extending parallel to said guide and a nut member in meshing engagement with said bar member, one of said members being mounted on each said block and the other of said members being mounted on said guide, mean-s preventing rotation of one of said members and means for rotating the other of said members thereby to effect movement of said blocks along said guide.

9. An electrode according to claim 1 including means pivotally mounting said guide for movement about an axis parallel to its length.

10. An electrode for effecting an electrical surface treatment of polyethylene and other materials to render the surface thereof suitable for printing thereon, comprising an elongated guide,

two blocks slidably mounted on said guide,

an elongated flexible electrically-conducting element secured at spaced points on said guide and extending adjacent said guide and passing slidably through said blocks, and

means in each block defining a sliding path for said element, said sliding path extending away from the guide through one block and toward the guide through the other block whereby the portion of said element extending between the blocks is spaced further from said guide than the portions of said element on the opposite sides of said blocks whereby when the material to be treated passes on a surface facing said electrically conductive element, corona discharge from said element will be restricted to that portion of said element between the blocks which will be closer to said surface.

References Cited UNITED STATES PATENTS 2,856,533 10/1958 Rosenthal 250-495 r RALPH G. NILSON, Primary Examiner.

W. F. LINDQUIST, Assistant Examiner. 

1. AN ELECTRODE FOR EFFECTING AN ELECTRICAL SURFACE TREATMENT OF POLYETHYLENE AND LIKE MATERIALS TO RENDER THE SURFACE THEREOF SUITABLE FOR PRINTING THEREON, SAID ELECTRODE COMPRISING AN ELONGATED GUIDE, AN ELONGATED FLEXIBLE ELECTRICALLY-CONDUCTING ELEMENT EXTENDING ADJACENT SAID GUIDE, MEANS ANCHORING SAID ELEMENT AT TWO SPACED ANCHORAGE POSITIONS ON SAID GUIDE, TWO BLOCKS, MEANS MOUNTING SAID BLOCKS FOR INDEPENDENT SLIDING MOVEMENT ALONG SAID GUIDE INTERMEDIATE SAID ANCHORAGE POSITIONS, AND MEANS ON EACH SAID BLOCK ENGAGING SAID ELEMENT FOR IMPOSING A DEVIATION ON SAID ELEMENT SUCH THAT THE PORTION OF THE ELEMENT EXTENDING BETWEEN THE BLOCKS IS SPACED FURTHER FROM SAID GUIDE THAN THE ADJACENT PORTIONS OF THE ELEMENT WHEREBY WHEN THE MATERIAL TO BE TREATED PASSES ON A SURFACE FACING SAID ELECTRICALLY CONDUCTIVE ELEMENT, CORONA DISCHARGE FROM SAID ELEMENT WILL BE RESTRICTED TO THAT PORTION OF SAID ELEMENT BETWEEN THE BLOCKS WHICH WILL BE CLOSER TO SAID SURFACE. 